Photolyses of Dibenzyl Ketones in Liquid-Crystalline Media. The Fate of Benzyl Radical Pairs in Various Anisotropic Environments

Article abstract of DOI:10.1021/ja00330a043

Photolyses of 1-(4-methylphenyl)-3-phenylpropan-2-one (1a) and 1,3-diphenylpropan-2-one (1b) have been conducted in solid, liquid-crystalline, and isotropic phases of a 35/65 (w/w) mixture of cholesteryl chloride/cholesteryl nonanoate (CCl/CN), trans,trans-4'-n-butylbicyclohexane-4-carbonitrile (BCCN), or n-butyl stearate (BS).The fraction of in-cage recombination of benzyl radicals (F_c) produced upon decarbonylation of 1a depends strongly upon solvent phase.The effects of magnetic field upon F_c for 1a and the degree of isotopic enrichment of photolyzed 1b in mesophases are described.The results in BS, especially, indicate that solvent-containment barriers, whose origin does not lie in phase discontinuities or large polarity differences, can influence strongly F_c.